Fish Oil Safety and Side Effects

Fish oil is safe for most people. It can cause side effects including belching, bad breath, heartburn, nausea, loose stools, rash, and nosebleeds. Taking fish oil supplements with meals or freezing them can often decrease these side effects. Some fish meats are contaminated with mercury and other industrial and environmental chemicals. Fish oil supplements typically do not contain these contaminants.

Taking fish oil supplements can increase levels of the "bad" LDL cholesterol in some people. You will need blood tests periodically to ensure LDL cholesterols do not become too high.

High doses of fish oil might keep blood from clotting and can INCREASE the chance of bleeding.

Do not take fish oil if:

You have liver disease.

You are allergic to fish or seafood.

You have a condition called bipolar disorder.

You have an implantable defibrillator (a surgically placed device to prevent irregular heartbeat).

What is Fish Oil?

Fish oil can be obtained from eating fish or by taking supplements. Fish oil supplements are usually made from mackerel, herring, tuna, halibut, salmon, cod liver, whale blubber, or seal blubber.

Is Fish Oil effective?

Fish oils can significantly reduce blood levels of a kind of fat called triglycerides. This might help lower the chance of developing heart disease.

There is some scientific evidence that fish oils might have other benefits for the heart. Fish oils seem to help to prevent a second heart attack if started within hours of the first attack and continued for a year. Fish oils might also lower blood pressure in some people who have high blood pressure.

Fish oils might also be helpful for rheumatoid arthritis. People with rheumatoid arthritis seem to be less stiff in the morning if they take fish oils.

There is also some evidence that fish oils can help prevent migraine headaches in some people.

However, fish oils do not help atherosclerosis or "hardening of the arteries." They also do not seem to help for some other conditions people use them for such as gum infections, lupus, kidney or liver disease, or leg pain due to blood flow problems.

There isn't enough information to know if fish oils are effective for the other conditions people use them for, including: asthma, cancer, lung disease, hay fever, cystic fibrosis and many more.

Natural Medicines Comprehensive Database rates effectiveness based on scientific evidence according to the following scale: Effective, Likely Effective, Possibly Effective, Possibly Ineffective, Likely Ineffective, and Insufficient Evidence to Rate (detailed description of each of the ratings).